The Superplastic Properties and Microstructures Evolution of High Nb Ti₃Al Based Alloy

Abstract:

The superplasticity of high Nb Ti₃Al based alloy - Ti-23Al-17Nb (at.%) alloy sheet under the conditions of 940~1000°C and 5.5×10^-5s^-1~1.7×10^-3s^-1are studied. The results show the elongation changes as a parabola with the deformation temperature increasing, and the maximum elongation obtained at 960°C and 5.5x10^-5s^-1 is 1447.5%. Work hardening stage increases much more than softening stage when strain rate is decreased due to the increasing of element Nb. Compared with primary microstructure, the lath-like α₂ grains gradually disappeared, the α₂ grains became more equiaxed, and the content and size of α₂ grains are decreasing with increasing of deformation temperature. The volume fraction ratio of α₂ and β phase at the optimum deformation condition is 50:50%. The cavities mechanism at the fracture tip was discussed; it can be defined that the cavities could be avoided when deformation temperature is higher than 940°C.

• Periodical: Materials Science Forum (Volumes 838-839)
• Pages: 568-573
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.838-839.568
• Online since: January 2016
• Authors: Xiu Quan Han, Ming Jie Fu*
• Keywords: High Nb, Intermetallic, Microstructure, Superplasticity, Ti₃Al Based Alloy

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